1. Field of the Invention
The present invention relates generally to twin-shaft gas turbines, and more particularly, to controlling a gas generator in a twin-shaft gas turbine.
2. Description of the Related Art
Generally, a twin-shaft gas turbine includes a gas generator constituted by a compressor, a combustor, and a high-pressure turbine. This gas turbine also includes a low-pressure turbine (power turbine) connected to a load, with a gas generator shaft (a rotary shaft of the gas generator) being separated from a rotary shaft of the low-pressure turbine. In the gas generator, the compressor generates compressed air and supplies the compressed air to the combustor in which a fuel mixedly with the compressed air is then burned, thus combustion gases are generated. The combustion gases that have thus been produced by the combustor rotationally drive the high-pressure turbine to generate a driving force of the compressor. After this, the combustion gases are further sent to the low-pressure turbine to drive it for rotation.
In such conventional twin-shaft gas generator, control that provides angle control of the compressor inlet guide vane (IGV), based on a corrected rotation speed of the gas generator shaft, that is, corrected rotation speed responsive IGV angle control has been totally applied as most common gas-generator control, irrespective of an operational state of the gas generator.
The disclosures given in JP-2007-40171-A, JP-08-82228-A, and JP-63-212725-A, for instance, are known as examples of a twin-shaft gas generator.